1. Field of the Invention
This invention relates to an improved shaped-charge for a non-rotating projectile.
More particularly, this invention relates to a shaped-charge which, upon detonation, provides controlled deflection of a penetrating jet.
2. Description of the Prior Art
High explosive anti-tank (HEAT) rounds have been in the American arsenal since World War II. The penetration mechanism within the HEAT warhead is the shaped-charge. A shaped-charge consists of a thin-walled metallic cone (the liner) with high explosive molded around the outside of the cone. When the warhead reaches a preset stand-off distance from the target, the explosive is detonated. A shock front passes over the liner causing the liner to progressively deform and collapse upon itself. Under the extreme pressures of the explosion, the solid metallic liner converts to a semi-liquid or amorphous state. When opposing sides of the converging liner meet during collapse, a portion of the metal liner is "squirted" forward with high velocity (approx. 9 km/sec). This material comprising a train of discrete masses at high temperature moving at supersonic velocity is called the jet, and constitutes the penetrating element of the warhead. In the prior art, the flight axis of the jet is generally forward along the axis of symmetry of the warhead. Where guidance, target seeking or sensing components are located in a warhead ogive forward of the shaped charge, the amorphous jet must penetrate such components enroute to the target material which degrades its performance against the target.
The phenomena of shaped-charge or HEAT rounds is particularly important in deflecting enemy combat vehicles such as tanks. Such vehicles are defended primarily by two mechanisms; namely, (a) composition or internal structure of armor plates and sheets mounted on the vehicle, and (b) angle of obliquity presented to incoming anti-tank rounds by such plates or sheets.
Overcoming sloped armor system surfaces in enemy vehicles has been a major challenge to the U.S. Army over the years. Various techniques have been employed previously to accomplish this while more shallow obliquity angles are achieved to deflect incoming warheads. Having the projectile strikes the target while travelling a path of descending arc is one technique which lessens the effects of shallow obliquity of protective armor around the target. Recently, some projectiles have been constructed so that the penetration mechanism is built into the warheads that its penetration force is angularly displaced from the warhead axis of symmetry. Thus upon detonation, the penetrating mechanism of the warhead (a shaped-charge jet) leaves the projectile at a predetermined and built in displacement angle relative to the warhead axis or trajectory.
Each of the previous techniques used to overcome sloped armor defended targets carries with it some drawbacks. Having the projectile strike the target while travelling a descending arcuate path requires that the speed of the projectile be low enough to respond to aerodynamic forces as necessary to cause a continuously changing flight path. Having the projectile travel at low speeds introduces certain additional problems, one of which is that aiming a low speed projectile is considerably more difficult than aiming a high speed projectile. Incorporating the warhead obliquely into the projectile may eliminate the need to fire the projectile at a slow rate of speed. With this construction, the projectile can strike a sloped target surface ineffectively head-on, but the penetrating jet train travels along a path other than the flight axis of the warhead, thus overcoming successfully the target surface obliquity which defeats the projectile as it hits the target. However, this construction produces certain additional problems. Constructing the warhead at an angle in the projectile lessens the allowable size of the warhead for any given projectile diameter. An example of this phenomenon is as follows: if one were to build a shaped charge into the projectile at an angle of ninety degrees (so that the penetrating element would travel perpendicular to the center axis of the projectile), the allowable length of the shaped charge could not exceed the projectile diameter. For built in obliquities or angles between zero (conventional) and ninety degrees (perpendicular), the allowable length of the shaped charge is decreased from a maximum effectiveness length criterion to the projectile diameter, thus comprising its lethality or penetration effectiveness.